This invention relates generally to x-ray tubes used in imaging systems and more particularly, to a switching unit to control the duration and magnitude of x-ray beams transmitted from an x-ray tube.
In at least one known imaging system configuration, an x-ray source projects an x-ray beam. The x-ray beam passes through an object being imaged and after being attenuated by the object, impinges upon a radiation detector. The intensity of the attenuated beam radiation received at the detector is dependent upon the attenuation of the x-ray beam by the object. The detector produces an electrical signal that is a measurement of the beam attenuation. A plurality of attenuation measurements are acquired to produce an image of the object.
The x-ray source, sometimes referred to as an x-ray tube, typically includes an evacuated glass x-ray envelope containing an anode, a control grid and a cathode. X-rays are produced by applying a high voltage across the anode and cathode and accelerating electrons from the cathode against a focal spot on the anode by applying a high voltage to the x-ray tube control grid.
At least one known imaging system includes a costly grid control power supply as a means of turning on and off the control grid voltage for controlling x-rays from the x-ray source.
It would be desirable to provide a switching unit, or circuit, which adjusts the signals applied to the x-ray source so that the magnitude and duration of the x-ray beams emitted from the x-ray tube are altered. It would also be desirable to provide a switching unit which includes any number of modular switching elements which may be combined to provide incremental control of the tube signals as required by the application while minimizing cost of the switching unit. Additionally, it would also be desirable to provide such a unit which utilizes a beam or beams of light to control the switching elements to provide isolation from the high voltage tube signals.